Field of the Invention
The present invention relates to a method and an apparatus for detecting a streak, and a printing apparatus, and more particularly to a detection technique of detecting a streak represented by a streak defect and the like of printed material by using image processing.
Description of the Related Art
A method disclosed in Japanese Patent Laid-Open No. 2001-297321 (Patent Literature 1) is known as one of methods for inspecting for a print defect in printed material. Patent Literature 1 discloses the method of comparing an edge image extracted from an inspection image taken from printed material with a color camera with a preformed reference image to detect edge information included only in the inspection image as a defect in the printed material. According to Patent Literature 1, the edge image is formed by performing spatial filtering using a typical edge enhancement filter represented by a Laplacian filter (refer to paragraph [0027] and FIG. 4 of Patent Literature 1).
The method shown in Patent Literature 1 is a detection method based on a fact that a print defect has a high frequency component in a spatial frequency domain in many cases, and is particularly suitable for detecting an isolated point-like defect in printed material.